import sys
import pygame
from bullet import Bullet
from alien import Alien
import sys
from time import sleep

def fire_bullet(ai_settings,screen, ship, bullets):
    """如果还没有达到限制，就发射一发子弹"""
    #创建子弹，将其加入到编组bullets
    if len(bullets) < ai_settings.bullets_allowed:
         new_bullet = Bullet(ai_settings, screen, ship)
         bullets.add(new_bullet)    
def check_keydown_events(event, ai_settings,screen, ship, bullets):
   """响应按键"""
   if event.key == pygame.K_RIGHT:
        ship.moving_right = True
   elif event.key == pygame.K_LEFT:
        ship.moving_left = True
   elif event.key == pygame.K_SPACE:
       fire_bullet(ai_settings, screen, ship, bullets)
   elif event.key == pygame.K_Q:
       sys.exit()
def check_keyup_events(event, ship):
    if event.key == pygame.K_RIGHT:
        ship.moving_right = False
    elif event.key == pygame.K_LEFT:
        ship.moving_left = False
def check_play_button(stats, play_button, mouse_x, mouse_y, aliens, ship, screen, bullets, ai_settings, sb):
    """再玩家单击Play按钮时开始游戏"""
    button_clicked = play_button.rect.collidepoint(mouse_x, mouse_y)
    if button_clicked and not stats.game_active:
        #隐藏光标
        pygame.mouse.set_visible(False)
        #重置游戏统计
        stats.reset_stats()
        stats.game_active = True

        #重置记分牌图像
        sb.prep_score()
        sb.prep_high_score()
        sb.prep_level()
        sb.prep_ships()
        #清空外星人列表和子弹列表
        aliens.empty()
        bullets.empty()

        #创建一群外星人，并让飞船居中
        create_fleet(ai_settings, screen, ship, aliens)
        ship.center_ship()


def check_events(ai_settings,screen, ship, bullets, stats, play_button, aliens, sb):
    """响应鼠标和按键事件"""
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            sys.exit()
        elif event.type == pygame.KEYDOWN:
          check_keydown_events(event, ai_settings, screen, ship, bullets)              
        elif event.type == pygame.KEYUP:
          check_keyup_events(event, ship)
        elif event.type == pygame.MOUSEBUTTONDOWN:
            mouse_x, mouse_y = pygame.mouse.get_pos()
            check_play_button(stats, play_button, mouse_x, mouse_y, aliens, ship, screen, bullets, ai_settings, sb)

def check_alien_collisions(ai_settings, screen, ship, aliens, bullets, stats, sb):
    """响应子弹和飞船的碰撞"""
    #检查子弹是否击中外星人，如果是就删除对应的子弹和外星人
    collisions = pygame.sprite.groupcollide(bullets, aliens, True, True)

    if len(aliens) == 0:
        #删除现有子弹并新建一群外星人
        bullets.empty()
        ai_settings.inscrease_speed()

        #提高等级
        stats.level += 1
        sb.prep_level()

        create_fleet(ai_settings, screen, ship, aliens)

    if collisions:
        for aliens in collisions.values():
           stats.score += ai_settings.alien_points * len(aliens)
           sb.prep_score()
        check_high_score(stats, sb)

def update_bullets(ai_settings, screen, ship, aliens, bullets, stats, sb):
    """更新子弹位置，并删除以消失的子弹"""
    #更新子弹位置
    bullets.update()
    #删除已消失的子弹
    for bullet in bullets.copy():
        if bullet.rect.bottom <= 0:
            bullets.remove(bullet)
    check_alien_collisions(ai_settings, screen, ship, aliens, bullets, stats, sb)

def update_screen(ai_settings, screen, ship, aliens, bullets, play_button, stats, sb):
    """更新屏幕上的图像，并切换到新屏幕"""
    #每次循环时都重新绘制屏幕
    screen.fill(ai_settings.bg_color)
    for bullet in bullets.sprites():
        bullet.draw_bullet()
    ship.blitme()
    aliens.draw(screen)

    #显示得分
    sb.show_score()
    #如果游戏处于非活动状态就显示Play
    if not stats.game_active:
        play_button.draw_button()
    #pygame.display.flip()将不断更新屏幕，以显示元素的新位置，并在原来的位置隐藏元素，从而营造平滑移动的效果。
    pygame.display.flip()

def get_number_rows(ai_settings, ship_height, alien_height):
    """计算屏幕可容纳多少行外星人"""
    available_rows = (ai_settings.screen_height - (3 * alien_height) - ship_height)
    numbers_rows = int(available_rows / (2 * alien_height))
    return numbers_rows


def get_number_aliens_(ai_settings, alien_width):
    """计算可容纳多少个外星人"""
    available_space_x = ai_settings.screen_width - 2 * alien_width
    number_aliens_x = int(available_space_x / (2 * alien_width))
    return number_aliens_x

def create_alien(ai_settings, screen, aliens, alien_number, row_numbers):
    """创建一个外星人并加入当前行"""
    alien = Alien(ai_settings, screen)
    alien_width = alien.rect.width
    alien.x = alien_width + 2 * alien_width * alien_number
    alien.rect.x = alien.x
    alien.rect.y = alien.rect.height + 2 * alien.rect.height * row_numbers #这个编组类似于一个二维数组吗
    aliens.add(alien)

def create_fleet(ai_settings, screen, ship, aliens):
    """创建外星人群"""
    #创建一个外星人，并计算一行可容纳多少个外星人
    alien = Alien(ai_settings, screen)
    number_aliens_x = get_number_aliens_(ai_settings, alien.rect.x)    
    number_rows = get_number_rows(ai_settings, ship.rect.height, alien.rect.height)
    #创建外星人群
    for row_number in range(number_rows):
        for alien_number in range(number_aliens_x):
             create_alien(ai_settings, screen, aliens, alien_number, row_number)
    

def change_fleet_direction(ai_settings, aliens):
    """将整群飞船下移，并改变方向"""
    for alien in aliens.sprites():
        alien.rect.y += ai_settings.fleet_drop_speed
    ai_settings.fleet_direction *= -1

def check_fleet_edges(ai_settings, aliens):
    """有飞船到达边缘做出措施"""
    for alien in aliens.sprites():
        if alien.check_edges():
            change_fleet_direction(ai_settings, aliens)
            break

def ship_hit(ai_settings, stats, screen, ship, aliens, bullets, sb):
    """响应被外星人撞到的飞船"""
    if stats.ships_left > 0:
        #将ship_left减一
        stats.ships_left -= 1

        #更新记分牌
        sb.prep_ships()
        #清空外星人列表和子弹列表
        print(stats.ships_left)  # 打印剩余飞船数量
        aliens.empty()
        bullets.empty()

        #创建一群新的外星人，并将飞船放到屏幕底部中央
        create_fleet(ai_settings, screen, ship, aliens)
        ship.center_ship()

         #暂停
        sleep(0.5)
    else:
        stats.game_active = False
        pygame.mouse.set_visible(True)

    


def check_aliens_bottom(ai_settings, stats, screen, ship, aliens, bullets, sb):
    """检查是否有外星人到达屏幕底端"""
    screen_rect = screen.get_rect()
    for alien in aliens.sprites():
        if alien.rect.bottom >= screen_rect.bottom:
            #像飞船被撞到一样处理
            ship_hit(ai_settings, stats, screen, ship, aliens, bullets, sb)
            break

    
def update_aliens(ai_settings,stats, screen, ship, aliens, bullets, sb):
    """检查飞船位置是否处于边缘，更新外星人群中所有外星人的位置"""
    check_fleet_edges(ai_settings, aliens)
    aliens.update()

    #检查外星人和飞船之间的碰撞
    if pygame.sprite.spritecollideany(ship, aliens):
        ship_hit(ai_settings, stats, screen, ship, aliens, bullets, sb)
    #检查是否有外星飞船到达屏幕底端
    check_aliens_bottom(ai_settings, stats, screen, ship, aliens, bullets, sb)
    
def check_high_score(stats, sb):
    """检查是否产生了最高分"""
    if stats.score > stats.high_score:
        stats.high_score = stats.score
        sb.prep_high_score()